Method of producing fibers of different diameters simultaneously and of producing glass paper therefrom



2,884,681. IAMETERS y 1959 D; LABINO METHOD OF PRODUCING FIBERS OFDIFFERENT D SIMULTANEOUSLY AND OF PRODUCING GLASS PAPER THEREFROM 2Sheetse-Sheet l Filed Nov. 12, 1952 IN V EN TOR.

ATTORNEYS D. LABINO May 5, 1959 2,884,681

- METHOD OF PRODUCING FIBERS OF DIFFERENT DIAMETERS SIMULTANEOUSLYAND'OF' PRODUCING GLASS PAPER .THEREFROM Filed NOV. 12, 1952 2Sheets-Sheet 2 mm m QE 1 mm.

mi N United States Patent '0 METHOD OF PRODUCING FIBERS OF DIFFERENTDIAMETERS SIMULTANEOUSLY AND OF PRO- DUCING GLASS PAPER THEREFROMDominick Labino, Waterville, Ohio, assignor, by mesne assignments, toL.O.F. Glass Fibers Company, Toledo, Ohio, a corporation of OhioApplication November 12, 1952, Serial No. 320,076 6 Claims. (Cl. 28-723)This invention relates to glass paper and to methods of producing thesame; more particularly this invention relates to a paper in which theglass fibers constituting the paper have a plurality of diameters.

Glass fibers having a diameter of one micron or less, hereinafter termedsubmicron diameters or submicron fibers have been produced on aproduction basis as described in co-pending application of DominickLabino, Serial No. 273,012, filed February 23, 1952, now abandoned andassigned to the same assignee as the present invention. Such fibers havebeen shown to be useful in the production of glass paper as described inDominick Labino applications as follows:

Ser. No. 247,010 filed Sept. 17, 1951, now abandoned Ser. No. 256,930filed Nov. 17, 1951, Patent No. 2,658,-

Ser. No. 256,977 filed Nov. 19, 1951, Patent No. 2,692,-

Ser. No. 258,211 filed Nov. 26, 1951 Ser. No. 276,389 filed Mar. 13,1952, Patent No. 2,787,-

all assigned to the same assignee as the present invention.

The characteristics of the glass paper products described in thoseapplications render them particularly useful in electrical applications,chemical applications, as filters for smoke-laden air, sound insulationand so forth. It has been considered desirable however to increase thetensile strength of these papers above the 220# per square inch in a drycondition disclosed in co-pending application Serial No. 247,010referred to hereinbefore.

Accordingly a primary object of the present invention is to provide anovel glass paper of improved tensile strength.

Another object of the invention is to set forth methods of producing aglass paper of improved tensile strength.

These and other allied objectives of the present invention are attainedby subjecting primary glass fibers of varying diameters to a hightemperature, high velocity gas blast whereby the primary fibers areblown into submicron diameter fibers of varying diameters. The fibersare collected into a mat in which the fibers are so arranged that fibersof each diameter will have a complete or universal orientation in themat. Thereafter the fiber mat is wetted, compressed and dried to a paperlike sheet having a thickness of about 0.005 inch.

The increased tensile strength of the paper thus formed is considered tobe due to the fact that fibers of varying diameter which were present inthe mat readily interlock upon compression; further when a tensivestress is applied to such a paper it is considered that the vari ablesize fibers key or lock together to prevent undue extension andfracturing of the paper.

The submicron diameter fibers of the paper thus described may beproduced in several ways but it is preferred to form the primaryfilaments into a substantially planar group and to expose them to thegas blast simultaneously; with this mode of operation the larger sizeprimary fibers will sufier less attenuation than the smaller fibers butall the attenuated fibers will be of submicron diameter.

Alternatively several gas blasts may be employed operating concurrentlybut on different size primary fibers, the blown fibers produced from theseparate blasts being collected on a common surface to achieve the matof complete fiber orientation.

The invention will be more fully understood by reference to the detaileddescription and the accompanying drawing wherein:

Figure 1 schematically illustrates apparatus useful in the process ofinvention including a glass melting pot;

Figure 2 is a bottom view of the aperture plate of the melting pot takenon line 2--2 of Figure 1;

Figure 3 is a sectional view of a nipple useful in the aperture platefor controlling primary fiber diameter;

Figure 4 is a cross-sectional view of one form of melting pot includingan aperture plate;

Figure 5 illustrates a further embodiment of the invention;

Figure 6 illustrates another embodiment of the invention;

Figure 7 illustrates an aperture plate useful with the structure ofFigure 6; and

Figure 8 illustrates drawing rolls useful with the apparatus of Figure6.

Referring to the drawings there is shown in Figure 1 a glass melting pot10 of platinum or suitable alloy for the heating and melting of glassmarbles which are fed from hopper 14 in response to the actuation ofsolenoid 16 which is itself governed by the depth of molten glass in thepot. Accordingly a constant glass level is maintained in pot 10.

The lower end of pot 10 terminates in an aperture plate 18 havingapproximately holes the arrangement of which is most clearly indicatedin Figure 2. The apertures 20 of the plate may be of a uniform size butare adapted to receive open ended nipples 22 (Figure 3) which may haveinternal diameters of varying sizes. Thus the nipples may be chosen toprovide primary glass filaments which range in size from 0.002 to 0.007inches. Alternately as will be described hereinafter the nipples may allbe of one size and the rate of drawing the filaments may be varied tosecure the various sizes of primary filaments. While a structuralarrangement of the aperture plate and nipple is presently known whichproduces primary fibers or filaments of a given size, it has not so faras is known been suggested to produce multiple size filaments from asingle pot.

The pot as indicated in Figure 4 is circular and the circular apertureplate (Figure 2) is provided with a plurality of concentrically arrangedapertures adjacent the periphery thereof. Induction heating coil 24(Figures 1 and 4) suitably adapted for connection with a source of highfrequency energy is placed around the pot at substantially the glassmelting level 25 and the pot (Figure 4) is provided with insulation, asceramic material 27. As disclosed in copending application Serial No.273,012, filed February 23, 1952, now abandoned, assigned to the sameassignee as the present invention, such an arrangement contributes tothe production of uniform primary filaments.

Positioned below the glass melting pot 10 are two sets of shafts 26, 28and 30, 32 driven by suitable means (not shown) and upon which aremounted drawing rolls as indicated generally at 34. In the operation ofthe apparatus the primary filaments pass between and are drawn by thedrawing rolls. In the practice of this invention the shafts 26, 28 aredriven at one speed and the shafts 30, 32 at a higher speed. Highdrawing rates normally produce smaller filaments and consequently thecombination of variation in drawing rate with changes in aperture sizespermit a high degree of controlled variation in the primary filament.

Snubber shafts 36, 38 are positioned between the pot and drawing rollsand serve with the drawing rolls to align the filaments or primaryfibers into a single plane. The snubber shafts are grooved to receivethe fibers and are preferably driven to avoid undue and impositivefrictional effects. The primary fibers pass from the drawing rolls andare advanced thereby over the flat face 40 of a guide block 42 having aV-shaped forward edge 44; the fibers as they approach edge 44 it will benoted are in a substantially vertical planar arrangement.

In horizontal alignment with edge .4 is a gas burner 46 having adischarge slot 48 through which a high temperature high velocity gasblast may be discharged at the ends of the glass fibers as they passedge 54. The heat of this blast causes the ends of the fibers to bemelted and the force of the gases causes the molten glass of each of thefibers to attenuate into very fine diameter fibers that is fibers havinga diameter of one micron and less. Blast conditions which occasion thiseffect include gas temperatures of about 3300 F. and blast velocities of1600-2000 ft. per second, with the primary fiber diameter having a rangeof 0.002 to 0.007 inches. The rate of feed While a consideration is notcritical and need not be uniform in feet per minute of vertical travelfor all primary fibers. Since the melting rate of the large diameterfibers will be somewhat slower than the others the speed should ingeneral be predicated upon the melting time of the larger diameterfiber.

The glass blown into submicron diameter fibers must for the attainmentof the objectives of this invention be so collected into a mat form asto provide a complete or substantially uniform orientation of thesubmicron fibers of different diameters. Thus fibers blown from aprimary fiber or filament having a diameter of 0.002 inches may attain adiameter in the blown fiber form as low as 0.04 microns While primaryfibers of a diameter of 0.007 result under the conditions stated ofblown fibers having a diameter of up to one micron. The fibers of 0.04micron for example must in the mat extend in all directions andsimilarly for those of other diameters.

To attain this complete or universal orientation, the collecting meansmay be positioned at a sufiicient distance from the blast as to permitthe staple fibers to be jockeyed out of a straight line flow by eddiesin the gases of the blast; thus the collecting means may itselfpreferably be a foraminous belt 5-0 mounted on pulleys 52, 54 and drivenby suitable means (not shown) in the direction of the arrow (Figure l).A hood 56 may 'be positioned over the upper strand and a suction box 58may be mounted at the end of the hood beneath the upper strand to drawthe staple to the belt. The downwardly depending end 60 of the hood 56may be employed to receive a large proportion of the blown material andto direct it to the belt, or it may be sufficiently distant from theblast to merely serve as a stop in which case it will play substantiallyno part in fiber orientation.

As illustrated in Figure 6 the foraminous belt as 62 may pass verticallyupward, the fibers passing through hood 64 being subjected to a slightdraft through opening 66 to induce complete orientation.

Referring again to Figure l the fibers on the horizontal belt 50, formedinto mat 68, pass from beneath the hood 56 under a water spray '70 whichcondenses the loose fibrous mat into a Wet felted mat of reducedthickness; when compacted as described the Wet material has, due to thehomogeneous web structure and the interlaced fibers of varying diameter,a very considerable strength, and may be readily handled or pressured toa thinner paper form without destructive results.

Accordingly to form the paper the continuous length mat is passed beforea heater 72 to partially dry the material before it enters between pressrolls 74, 76; the pressured material is then dried preferably underinfra-red light as at 78 and then reeled as at 80.

The product thus attained is a true paper having a thickness of onlyabout .005 inch, which however as may be readily noted involves aconsiderable number of individual fibers of submicron diameter in orderto attain this thickness. The tensile strength of such a paper in boththe dry and wet condition, due to the interlocking and keying of thefibers of different diameters, will be improved materially.

Figure 5 illustrates another embodiment of the inventive process whereina plurality of filament forming units and gas burners are employed; inthis figure the same (where applicable) numerals as used in Figure l areemployed with the exception that primes and double primes are utilized.In this instance the filaments fed to a given burner may be of a singlesize and the collecting means may be so positioned as to receive thestaple fiber of one size and then the staple of another submicron size;it is of course possible here also to feed several sizes of primaryfilaments to each burner if desired. The product attained in thisinstance may however have slightly different surface conditions onopposing sides since the predominant fiber size on each side will bedifferent. The fiber orientation however will still be substantiallycomplete, the paper strength greater than that hitherto known and aboutthe same as that of the product previously described herein.

With the employment of this latter embodiment or modifications thereofusing plural filament systems care should be exercised in thepositioning of belt 50 in order to obtain the desired orientation offibers of all sizes; otherwise the apparatus and process is similar tothat described in connection with Figure 1, except that only one set ofdrawing rolls designated at 83 and 85 respectively is required for eachdevice.

The embodiment of Figure 6 is particularly useful where the size of thenipples in the aperture plate 118 is uniform as set out in Figure 7. Theglobules of molten glass forming at these nipples normally would be veryuniform and would produce with normal drawing primary filaments ofuniform size from pot 110 which is fed from hopper 114 with glassmarbles, upon actuation of solenoid 116. However since it is desirableto supply filaments of several different diameters in planar arrangementto the blast from the burner 146 a novel arrangement of drawing rolls isprovided to service this purpose.

Thus shafts 126 and 128 like shafts 26 and 23 of Figure 1 have members127, 129, 136 and 138 of resilient material mounted thereon but in thisinstance the diameters vary slightly to accommodate different sizeprimary filaments; that is the portions 127 and 129 have a greatersurface speed than the portions 131 and 133 since the speeds of theshafts 126 and 128 are equal. The higher drawing speed between portions127 and 129 will result in a smaller primary filament from a given glassglobule as compared with that attained between portions 131 and 133. Thevariation in roll diameter of course need only be very slight sincefilaments under consideration vary only between 0.002 and 0.007 inch.This arrangement permits the feeding to the flame of the burnerfilaments of a plurality of sizes since the filaments passing betweenthe rolls 135, 137 and 142, 144 on shafts and 132 may vary as desiredand the shaft speeds themselves may be variable.

Accordingly as indicated in Figure 8 four sizes of filaments may beproduced as at 150, 152, 154 and 156; the only essential requirement inthis connection is that the feed speed and flame as stated hereinbefore,be capable of producing micron or submicron diameter fiber.

The product of invention whatever apparatus is employed isadvantageously produced having fibers in a definite ratio of diametersizes. Thus some of the fibers may have a diameter of approximately onemicron while others have diameters of 0.75, 0.50 and 0.25 micron. Thefibers of a given paper may be even multiples, that is, 0.25, 0.50 andone micron or may be odd multiples as 0.25 and 0.75 or both odd and evenas indicated hereinbefore. The primary fiber diameter may of course varyslightly from a given mean and this variation will be reflected to aslight extent in the blown fiber but is not sufiiciently critical toafiect the desired result.

The length of the blown fibers will be at least 500 to 1000 times theirdiameters, a factor which assists in attainment of the universalorientation. The relatively long fiber length also induces some doublingof the individual fibers which aids the distribution and keying effect.

The long traverse in hood 64 of Figure 6 is particularly efficacious inthis respect and the paper resulting from the partial drying by heater172, the compression by rolls 174 and the final drying at 178 is ofsuperior quality.

It will be understood that this invention is susceptible to modificationin order to adapt it to different usages and conditions and accordingly,it is desired to comprehend such modifications within this invention asmay fall within the scope of the appended claims.

I claim:

1. In a process of producing glass paper the steps of drawing from asingle glass melting pot a plurality of primary filaments the diametersof which are in ratio of 4:3:2z1, feeding the primary fibers to a hightemperature high velocity gas blast to blow the primary fibers intofibers of varying submicron diameters, which diameters are in the ratioof 4:3:2z1, collecting the blown fibers into a mat in which the fibersof each diameter are universally oriented, wetting the mat to reduce thethickness thereof, compressing the wetted mat, and thereafter drying themat.

2. In a process of producing glass paper the steps of drawing primaryglass fibers of difierent diameters from separate molten glass sourcesand such that the diameters of the fibers are in the ratio of 4:3:2z1,separately blowing the primary fibers from each source into submicrondiameter fibers which difier in diameter in accordance with thevariations in the primary fiber diameters, collecting the blown fibersinto a single mat in which the fibers of each diameter have asubstantially universal orientation, wetting the mat to reduce thethickness thereof, compressing the wetted mat, and thereafter drying themat.

3. In a process of producing glass paper the steps of drawing primaryglass fibers at different linear speeds from a source of molten glass toproduce primary fibers of varying diameters and such that the fiberdiameters are in the ratio of 4:3:2z1, blowing the primary fibers intofibers of varying submicron diameters such that the diameters are in theratio of 4:3:2z1, and collecting the blown fibers into a single mat inwhich the fibers of each diameter have a substantially universalorientation.

4. A process of producing glass paper, comprising blowing continuousprimary filaments of differing diameters into fibers of varyingsub-micron diameter, mixing said fibers together and collecting themixed fibers into a mat, wetting the mat to reduce the thicknessthereof, compressing the wetted mat, and thereafter drying the mat.

5. A process of producing glass paper as defined in claim 4, wherein theprimary filaments are disposed in a substantially common plane prior tothe blowing thereof.

6. A process of producing glass paper as defined in claim 5, wherein thefilaments are blown into fibers by a blast of hot gases which carriesthe fibers in suspension away from the filaments, and wherein the fibersare collected into a mat at a point sufl'iciently distant from thefilaments that eddies form in the gases, which eddies mix together thesuspended fibers.

References Cited in the file of this patent UNITED STATES PATENTS2,057,393 Powell Oct. 13, 1936 2,395,371 Dockerty Feb. 19, 19462,511,381 Stevens June 13, 1950 2,565,941 Barnard Aug. 28, 19512,658,848 Labino Nov. 10, 1953 2,751,962 Drummond June 26, 1956

